With the rapid developments of the electronic technology and the communication technology, some electronic devices, such as mobile phones, have become indispensable parts of people's daily lives. They integrate many functions, and bring great conveniences to people's lives and works.
One of the functions is to play audio data such as music or speeches through a stereo, which uses two or more independent sound effect channels and appears on a pair of speakers (e.g., horns) arranged symmetrically. The sound generated in such a method is kept natural and melodious in various directions.